Could two time zones help electricity demand?

South Africa should consider the introduction of two time zones in order to alleviate Eskom’s electricity peak-demand woes, said Professor Christo Viljoen, a professional electrical engineer and former member of the then-Eskom council, this week.

“If South Africa is ... divided into two time zones, east and west, with an hour difference between the two, the peak demand of the two zones will not coincide.

“This will flatten the national peak demand of electricity appreciably, although it would not bring relief to the Western Cape’s peak-demand problems,” he said.

“Depending on where the border for the two zones is drawn, the national peak demand could save as much as the equivalent of one power station, [which has] the equivalent generation capacity of Koeberg,” he added

He told the Mail & Guardian Online that he is surprised that this idea has not been investigated by Eskom before, and that peak-electricity demands “are a big problem for Eskom”.

“Australia does this. America has four or five time zones. So it’s not something that is uncommon. People will get used to it,” said Viljoen.

Andrew Etzinger, general manager responsible for Eskom’s demand-side management programme in the Western Cape, told the M&G Online that the introduction of two time zones will only assist with electricity peak demands to a “very limited extent”.

“The cost of the initiative to the broader economy in terms of additional infrastructure and inconvenience would need to be very carefully considered. And it is doubtful that peak-electricity demand savings alone could justify the cost,” he said.

Eskom are open to all innovative ideas towards cost-effective reduction of electricity demand nationally and in the Western Cape, said Etzinger.

“Unlike the demand-side management initiatives introduced in the Western Cape, a time-zone approach would not save energy and the two approaches cannot therefore be compared,” he said.

Contrary to Viljoen’s claims, Eskom embarked on a study, undertaken a few years ago, which concluded that two separate time zones would have “no significant benefit”, said Etzinger.

“However, electricity demand in the Cape has grown substantially in the last few years and we will update our calculations to see if anything has changed,” he said.

Professor Ian Jandrell, head of department at the School of Electrical and Information Engineering at the University of the Witwatersrand, told M&G Online that Viljoen’s proposal makes sense; that the introduction of two time zones in South Africa may be a positive move, but that it would need to be evaluated carefully.

“As a principle, shifting the times of peaks makes good sense, so a proper study should be done. We would need to understand the potential benefit of a one-hour time zone shift against the present nature of the peak load across South Africa—in particular the present energy usage cycles in the two proposed zones.

“The peaks may occur over a relatively long period ... and then a one-hour shift may not have the anticipated impact. My sense is that one hour may indeed not be enough for a significant impact. This is not to knock the proposal, but as any engineer will always tell you, ‘it depends’,” said Jandrell.

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